Three female bystanders, aged between 60 and 82, were hit by police bullets or bullet fragments.

Alleged knife attacker Jerry Sourian at Westfield Hornsby with an injured bystander in the background.

Photo: Channel Nine

Advertisement

Several sources close to the investigation have told Fairfax Media that Mr Sourian was involuntarily placed in Hornsby Hospital's Mental Health Intensive Care Unit a few weeks ago due to schizophrenia.

His doctor's report said he should not be released under any circumstances.

This decision was partly to do with the fact he had expressed homicidal tendencies towards police.

However, a senior doctor overruled the advice and allowed him to leave the hospital for one hour a day, Fairfax Media has been told.

An injured bystander is treated after being caught in crossfire when police shot at Jerry Sourian at Westfield Hornsby.

Photo: Channel Nine

Last week, he absconded while on day release and somehow flew to Melbourne. He was brought back to the mental health facility but was again granted day release.

On Wednesday, as he was leaving Hornsby Hospital for his approved hour of leave, he had a heated argument with three family members.

The crime scene at Westfield Hornsby where people were injured after officers opened fire on a man with a knife.

Photo: Janie Barrett

His family ran back inside to seek help and a clinical aggressive response team was activated at 11.57am.

However, by the time security arrived at 12.05pm, Mr Sourian had disappeared.

There were only two security staff on duty and they were at the other side of the hospital when the alert was raised.

For more than five years, security guards at Hornsby Hospital have been asking for more staff.

The Health Services Union has been calling for a dedicated mental health security presence at the hospital. Had one been working, Mr Sourian might have been prevented from absconding.

"Having only two staff on for a major metropolitan hospital with seven mental health units is just untenable," said Nathan Sing, a Health Services Union delegate and security guard at Hornsby Hospital. "We desperately need more staff."

Assistant Commissioner Denis Clifford said police were alerted when Mr Sourian absconded on Wednesday and officers had been making efforts to try to locate him.

Two police officers who arrived at Westfield Hornsby on Thursday initially tried to calm Mr Sourian.

Mr Clifford defended the officers' decision to draw their guns, rather than Tasers. Footage shows a female officer firing at Mr Sourian as he walked towards her with the knife.

"​A decision was made by those officers in a life and death situation," he said.

He said there were "only a matter of metres" between the man and the officers who had only a "matter of seconds" to act in the "confined area of the shopping mall".

"I wonder what might have happened if the police had not intervened and stopped this person with the knife," he said.

In that incident, a police officer and security guard were almost shot dead by a patient on ice.

"We have seen no substantive increase in hospital security, just bureaucratic waffle and inertia," he told Fairfax Media on Friday.

"What has happened in Hornsby is deeply regrettable, especially when it may have been preventable.

"The government needs to address hospital security staffing with genuine urgency."

Police have launched a critical incident investigation.

NSW Health and the Northern Sydney Local Health District have launched a review into the Hornsby Hospital incident, led by NSW Chief Psychiatrist Dr Murray Wright.

A spokeswoman for NSW Health said the patient was released into the care of family members and allowed to access the hospital grounds.

She said almost all patients who are admitted involuntarily undergo a "graduated leave process prior to departure".

"Graduated leave from inpatient facilities is an important part of the inpatient therapeutic process," she said.

"Leave is granted on the basis of clinical and risk assessment, informed by a number of factors, including past history, information from carers and clinical presentation."

Loading

Update: A NSW Health spokeswoman has denied Mr Sourian had threatened to harm police or that a consulting psychologist overruled advice not to allow day release.

"All treatment decisions were made by the patient's treating psychiatrist and the decision for him to be allowed an hour's leave with his family in the grounds of the hospital was made by that psychiatrist in consultation with the family," the spokeswoman said.